Known vehicle systems include one or more propulsion-generating vehicles or units and, in certain cases, one or more non-propulsion-generating vehicles or units connected with each other to travel along a route. The propulsion-generating vehicles supply tractive force to propel the propulsion-generating vehicles and non-propulsion-generating vehicles along a route.
The tractive force required to propel the propulsion-generating vehicles and non-propulsion-generating vehicles along the route may vary due to various parameters, such as vehicle system length, vehicle system weight, grade of the route, route conditions, weather, and performance characteristics of the propulsion-generating vehicles, among others. For example, a vehicle system traveling through strong winds may require a greater tractive force than otherwise would be necessary in order to overcome the drag force on the vehicles from the wind. In another example of how weather affects required tractive forces, rain or other precipitation on rails may require more power from locomotives on a vehicle system due to less adhesion between the wheels of the locomotive and the rails. In yet another example, weather may affect required tractive forces by affecting the weight of the vehicle system, such as in the case of a gain in mass due to retention of rain water in non-propulsion-generating vehicles.
Presently, trips taken by vehicle systems may be planned with a focus on energy efficiency. To enhance efficiency, vehicle system trip planning may take into account many parameters, such as the parameters mentioned above and more. Accurate calculations of weight and other parameters are important for trip planning purposes in order to improve handling and control of the vehicle system during the trip.
When the parameters relied on during trip planning are not accurate, the vehicle system may have to undergo a trip re-plan, which is a re-adjustment. For example, the weight of a vehicle system relied on during trip planning may be the sum of the individual weights of the vehicles in the vehicle system (when empty) with the weight of cargo added. However, if the vehicle system travels through a rain storm during its trip, each vehicle may retain, for example, two extra tons of rain water. If each of the vehicles weighed 100 tons dry, then each now weighs 102 tons, which is a 2% increase in weight from the added water mass. The trip was planned for a vehicle system weighing 2% less than the vehicle system now weighs, so the vehicle system may have to undergo a trip re-plan based on the weight discrepancy. Among other things, a trip re-plan is an opportunity loss because it represents that the vehicle system was not traveling as efficiently as the vehicle system would have been with more accurate parameters in the trip planning.